Differential injection rotary heater



July 1957 R. F. KRUPP ET AL 2,801,034

DIFFERENTIAL INJECTION ROTARY HEATER Filed Aug. 26, 1954 .Ezg..l.

' INVENTORS ROBERT F. KRUPR gmv K. WAGNER 70WW 7WWMWW ATTORNEYS United States Patent- Q DIFFERENTIAL INJECTION ROTARY HEATER Robert F. Krupp, San Lorenzo, and Jan K. Wagner, Oakland, Calif., assignors to Gerber Products Company, Fremont, Mich., a corporation of Michigan Application August 26, 1954, Serial No. 452,265

2 Claims. (Cl. 259-9) This invention relates to new and improved injection rotary heaters whereby steam or other hot fluid is mixed with a liquiform product to be heated. Reference is made to copending application Serial No. 332,476, filed January 21, 1953, for Agitating Heater, now Patent No. 2,726,851, granted Dec. 13, 1955.

More particularly, the present invention relates to a new and improved rotary impeller and orifice plate, the construction of which is hereinafter described in detail.

In heaters of the general type with which this invention is concerned, there is provided a cylindrical mixing chamber into which a product to be heated is introduced and into which a heating medium such as steam is separately introduced through an orifice plate having many small holes. The product and steam are brought together and mixed thoroughly by an impeller so that the steam is condensed and its heat is transferred to the product, thereby rapidly raising the temperature of the product.

The impeller hereinafter described comprises a rotatable disk having at its end adjacent the orifice plate a concave conical shape. The slope of the concave surface is such that the product entering at the center of the impeller flows outwardly at substantially constant velocity and pressure. The space between the conical surface of the impeller and the adjacent face of the orifice plate at any given diameter comprises ashort cylinder, the surface area of which is substantially equal to the cross sec u'onal area of the pipe through which the product flows into the chamber. 1

The result of the foregoing construction of the impeller, its distance from the orifice plate, and the cross sectional area of the pipe through which product is introduced into the mixing chamber results in a thin film of product flowing outwardly from the center toward the periphery of the impeller without change in radial velocity or pressure. Accordingly there is an even heating of the product throughout its travel and no overheating or underheating of any particular particle of the product, or burning thereof. The latter factor is important for the reason that if there is not an even heating of the product, although the average temperature recorded in temperature gauges which may be installed in the device will give a reading indicating no danger of adversely aifecting the taste or appearance of the product, nevertheless when even a small number of particles of product are overheated or underheated, the taste and appearance of the entire batch is adversely affected.

A further feature of the construction of the impeller as hereinafter set forth is the provision of a double row of pe s, the centers of each row being disposed in a spiral on the conical surface of the impeller, the pegs projecting outwardly from the face of the impeller toward the orifice plate and terminating a short distance therefrom. The pegs produce some agitation which can promote a more even transfer of heat from the steam to the product, but are primarily provided to produce a flat face in close proximity to the steam jet outlet to cause the steam to move transversely across the face of the orifice plate and clean away any material which might tend to gather around the circumference of each jet and eventually cause burn-on. The pegs as arranged and because of their diameter when rotated form the equivalent of a complete plane in close proximity to all jet holes in the orifice late. p The orifice plate provides a flat disk formed with holes placed in a pattern hereinafter described and separates a steam chest from the mixing chamber. The steam flows through the holes and contacts and is mixed with the product flowing on the opposite side of the orifice plate. One of the features characterizing the invention is the fact that the centers of the holes formed in the orifice plate are located along a double reverse spiral rather than in concentric rings. The hole locations along the spiral and the spiral radii are such that the quantity of steam added to the product as it flows radially across the plate is in proportion to the temperature differential between the product and the steam. The hole spacings are also modified slightly to correct for the difference in heat absorption qualities of the product as its viscosity changes. This arrangement of the holes concentrates the holes toward the center of the orifice plate which materially improves the heat transfer from the steam to the product. One reason for the improvement of the heat transfer is r the fact that the temperature differential between the steam and product is greatest at the point of entry of the product and hence concentration of the holes permits a more efiicient heat transfer. Another advantage of the described location of the holes is the fact that as the product is heated its viscosity increases and hence its ability to absorb heat decreases. When the steam is injected into the product at the time when its viscosity is least, the heat transfer is improved.

Still another advantage of the construction of the orifice plate is the fact that the location of the holes permits minimum spacing between the centers of the holes with maximum tendency to avoid steam bubbles or rings.

Another feature of the spiral arrangement of the holes in the orifice plate is the fact that the entire face of the impeller is swept by the holes, thereby eliminating burnon which sometimes occurs where concentric rings of holes are employed. In other'words, by the arrangement of the pegs on the impeller and the holes in the orifice plate, each is cleaned and burn-on prevented.

Other objects of the present invention will become apparent upon reading the following specification and referring to the accompanying drawings in which similar characters of reference represent corresponding parts in each of the several views.

In the drawings:

Fig. 1 is a longitudinal vertical section through a differential injection rotary heater formed in accordance with this invention.

Fig. 2 is an end elevation of the impeller as viewed along the line 22 of Fig. 1.

Fig. 3 is an end elevation of the orifice plate as viewed along the line 3-3 of Fig. l.

A short, cylindrical casing 12 open at one end and having a horizontal axis is provided, having a cylindrical interior chamber 11. The casing 12 is detachably mounted on a supporting base 13 in Which is suitably journalled a shaft 14 which extends through an aperture in the end of the casing opposite the open end thereof. Shaft 14 is rotated by an electric motor (not shown) at a high rate of speed and is supported by suitable bearings 16. A seal 17 is installed in the base 13 adjacent the casing 12 to prevent leakage of coolant from chamber 18 into the chamber 11 or leakage of the product from the chamber 11.

Beyond the open end of casing 12 is an annularly recessed circular body 19 which is formed with a central hub .21 provided with a circular operture in its center coaxial with shaft 14. Outside the hub 21 is an annular recessed'groove 22 which forms annular steam chest 23', the. outer diameter of the groove 22 being substantially the same as the inner diameter of the. chamber 11.

interposed between the casing 12 and the body 19 is a thin, apertured, annularofifice plate 24 which separates the chamber il from the steam chest 23. I One of the. features of the present invention is the pattern of the holes26 in the plate 24 which pattern is illustrated in Fig. 3. Theholeshave their centers located on centerli'nes 27 which comprise a double-pitch, reverse, substantially logarithmic expanding spiral pattern. The

, centers of the holes 26 (which are approximately 0.026

that'the centers of the holes are neither concentric nor do they lieon common radial lines reduces the tendency for bubbles or rings of steam to form in the mixing chamber." Further, the spiral configuration provides a substantially complete sweep of the entire impeller face and thus eliminates any tendency to allow the product to burn on the impeller in the areas between concentric steam orifice rings as is possible in prior art concentric ring patterns of holes. One of the important features of the spiral configurations is the resultant concentration of holes 26'toward the central axis of the heater which is highly desirable from a thermodynamic standpoint. The reasons for the desirability of such concentration are heretofore set forth. In accordance with the present invention, the percentage of holes in the inner one-third of the plate area is practically doubled as comparedwith the number of such holes in accordance with the best prior art hole patterns.

Around the edge of the plate is a sealing gasket 31, the plate 24 fitting inside a recess in the inner edge of the peripheralfiange of body 19 into which a projecting, annular ridge 32 on the open end of the casing also fits. A plurality of hinged, clamping bolts 33 mounted on casing 12 project through radial slots 34 in the periphery of body 19 so that when the nuts 36 on the ends of bolts 33 are tightened, the body 19; and casing 12 are drawn snugly together, plate 24 being clamped in position therebetween. By reason of gasket 31 fitting around the periphery of plate; 24, wear of gasket does not affect the tightness. of fit of body 19 against casing 12. Further, build-up of product around the juncture of the parts is prevented.

Steam enters the chest 23 through fitting 37 connected to a suitable source of steam under pressure, fitting 37 entering into an aperture in the back of the body and projecting into chest 23,*there being a deflector 38 in the end of fitting which insures that steam will circulate substantially. uniformly around chest- 23. Steam passes into the mixing chamber 28 through the. apertures 26 in plate 24.

The fluid product enters the mixing chamber through pipe 41 which is coaxial with the axis of shaft 14 and which extends through an aperture in hub 21 and a circular aperture 42in the center of plate 24. The inner diameter of pipe 41 flares adjacent its terminus and at its inner end is formed with an outwardly flared and rounded lip 43 which overlaps the circumference of aperture 42.

The exterior of conduit 41 is threaded as indicated by reference numeral 44 and said threads are engaged by nut 46, the inner end of which abuts ring 47 recessed for sealing gasket 48L By tightening nut 46, pipe 41 is drawn tov the right as viewed in Fig. 1, thereby tightening lip 43 against plate 24. It will be seenthat there are no 1 r 2,801,084 a l e 4 threaded joints between pipe 41 and the product comes in contact. Hence there are no threads in which the product may lodge, and cleaning is facilitated.

Impeller 51 is mounted on the end of shaft 14 lodging against shoulder 52 on shaft 14. Snap-ring 53 engagesJa groove adjacent the end of shaft 14 and retains the impeller thereon. A key 54is provided to impart rotative movement of shaft 14 to impeller'Sl.

Impeller 51 comprises a short cylindrical disk 56 of lesser diameter than chamber'll. Rim 57 around the periphery of disk adjacent the intake edge of the impeller limits the flow through the annular gap 58 between the periphery of the .rim 57 and theinner diameter of casing 12. lnwardly of the rim 5,7 the diameter of the impe ler is reduced so as to permit free flow of the product therethrough. A tangentially disposed discharge port 59 is provided in casing 12 through which the heated product is drawn ofi.

The face 61 of impeller 51 adjacent orifice plate 24 is concave and conical. The slope of the concavity of impeller face is calculated so that a practically constant velocity of flow of the product is obtained. This result is accomplished by making the depth of the concave surface 61 at several concentric circles of difierent diameters such that the depth multiplied by the square of each diameter assumes a constant value and approxi mately equals the cross-sectional area of pipe 41. An annular recess 62 is formed at the center of the im-' peller 51 opposite the lip 43 so as to permit the inflowing product to turn around the rounded lip. Hence, the radial velocity of flow through the heater is the same as the velocity through the inlet pipe 41 and this avoids any rapid changes of velocity. The space between the impeller face 61 and the orifice plate 24 comprises mixing chamber 28, which is small and permits the product to be dispersed as a thin film without change in radial velocity or pressure. Even heating of each particle of product is thus obtained and the'possibility of overheating or underheating a particular particle is avoided.

To agitate the thin film and also to provide a cleaning actionfor the orifice plate 24, a series of small diameter pegs 63 is inserted in the conical face 61 of the impeller, the axes of the pegs being parallel to the axis of rotation of the impeller. ings, a series of pegs. 63 positioned in six radial lines 64 across the face of the impeller is. provided. The center lines 66 of the pegs are positioned so as to form a doublepitch, reverse spiral. The outer ends of the pegs 63 extend to a uniform distance from the orifice plate 24 which is sufficient to prevent interference with rotative movement, provide a safety factor. for heat expansion of the various parts, and yet bring the ends of the pegs close enough to the orifice plate to clean the same and prevent build-up of product thereon. The diameter of pegs 63 is one-third the radial distance'between their center lines 66 so that the entire surface of orifice plate 24 is swept thereby when the impeller rotates.

In operation, upon assembly of the apparatus, the shaft 14 is rotated at a high rate of speed, the impeller 51 rotating with the shaft. The product, which is in fluid state, is forced by a pump (not shown) through inlet pipe 41. Steam is introduced through inlet 37 and is directed 1111iformly throughout chest 23, passing into the mixing chamber 28 through the apertures 26 in orifice plate 24. By reason of the concentration of the holes in the orifice plate around the center of the plate, the maximum inflow of heat is toward the center of plate 24. The product rounds the turn around the lip 43 andflows radially outwardly between the concave face 61 of the impeller 51 and the orifice plate 24. By reason of the thin film thus produced, a maximum amount of surface area of the product is exposed to steam. Hence, an intimate mixture of steam and product is produced which transfers the heat at the steam to the product and raises the temperature thereof substantially instantaneously. The pegs 63 on plate 24 with, which As shown inthe accompanying draw the surface 61 agitate the product moderately and hence facilitate the intimate mixture of the product and steam and increase the rapidity of temperature rise. The arrangement of the pegs 63 sweeps across the entire face of the orifice plate 24 and cleans the same for each revolution and at the same time the reverse spiral spacing of the holes 26 in the orifice plate 24 results in sweeping across the entire surface 61.

After thorough mixing, the product passes around the edge of the rim 57 and thence into the larger annular space 11 between the reduced diameter of the disk 56 and the casing 12 and out through discharge port 59.

To disassemble the apparatus, nuts 36 are loosened and body 19 removed. Pipe 41 and plate 24 are removed from body 19 by loosening nut 46. Impeller 51 is removed from shaft 14 by removing ring 53.- Re-assembly of the apparatus involves the reverse operations.

Although the foregoing invention has been described in some detail by way of illustration and example for purposes of clarity of understanding, it is understood that certain changes and modifications may be practiced within the spirit of the invention and scope of the appended claims.

What is claimed is:

1. A differential steam injection heater comprising a casing forming a mixing chamber, an orifice plate closing off one end of said casing, said plate having a plurality of small holes, a steam chest in back of said plate from which steam enters said chamber through said holes, a product inlet conduit projecting through said plate into said chamber, a product outlet conduit extending from said chamber, a shaft rotatably mounted and extending into said chamber, a disk mounted on said shaft in proximity to said plate, said disk having a concave, conical surface facing said plate, and a plurality of short pegs extending outward from said surface and terminating approximately in a common plane closely adjacent said plate, the centers of said pegs being arranged on the intersection of a plurality of radial lines and at least one expanding spiral.

2. A diiferential steam injection heater comprising a casing forming a mixing chamber, an orifice plate closing off one end of said casing, said plate having a plurality of small holes, a steam chest in back of said plate from which steam enters said chamber through said holes, a product inlet conduit projecting through said plate into said chamber, a product outlet conduit extending from said chamber, a shaft rotatably mounted and extending into said chamber, a disk mounted on said shaft in proximity to said plate, said disk having a concave, conical surface facing said plate, and in which the slope of said concave, conical surface is such that at any given diameter the area of the cylindrical space between the bottom of said surface and said plate is substantially equal and substantially equal to the cross-sectional area of said product inlet conduit, said holes in said plate having their centers spaced along a plurality of expanding spirals.

References Cited in the file of this patent UNITED STATES PATENTS 29,893 Lombard Sept. 4, 1860 352,414 Landolt Nov. 9, 1889 429,850 Eaton et al. June 10, 1890 1,533,409 Hartshorn Apr. 14, 1925 2,239,497 Byers Apr. 22, 1941 2,245,112 McLean June 10, 1941 2,252,076 Juterbock Aug. 12, 1941 2,352,767 Booth et a1. July 4, 1944 2,492,635 Hawk Dec. 27, 1949 FOREIGN PATENTS 236,382 Switzerland Feb. 15, 1945 

